Biology and You

You and Your Genes

What are some human characteristics controlled by one gene?

Some human traits are controlled by just one gene. They include the hitchhiker’s thumb (a recessive trait); tongue rolling (a dominant trait that is often debated as to whether it’s controlled by genetics); thumb crossing right over left (a recessive trait); a widow’s peak hairline (a dominant trait); attached earlobes (a recessive trait, although this is also highly debated by some scientists).